Study on the Effect of Hydra polymorphus on the Hatching Performance of Copepod Eggs

[Objective] The research aimed to discuss the feasibility of controlling the copepod outbreak of water-supply source by using biological method and provide references for the control of copepod outbreak in waterworks.[Method] The hatching time and average hatching rate of copepod eggs were measured after H.polymorphus's digestion of copepods.And the activity of the unhatched copepod eggs was detected.The effects of Hydra polymorphus on the hatching of copepod eggs were discussed.[Result] The hatching time of copepod eggs after H.polymorphus's digestion and egestion was 8-24 h and the average hatching rate of copepod eggs of mono-copepod and poly-copepods were 56.42% and 55.07% respectively.The unhatched copepod eggs were dyed by Trypan Blue,and these eggs were invaded by protozoon.In control group,the hatching rate of copepod eggs was 100%,and its hatching time were 8-16 h.[Conclusion] After H.polymorphus's digestion and egestion,the hatching rate of copepod eggs was obviously inhibited.